Switch mechanisms in automotive air-conditioning systems adopting a cable drive system in the known art include sliding switch mechanisms and knob switch mechanisms (see, for instance, patent reference literatures 1 and 2). Knob switch mechanisms that provide better operability and assure higher safety for driving than sliding switch mechanisms are preferred in most applications today (see, for instance, patent reference literature 3).    Patent reference literature 1: Japanese Unexamined Patent Publication No. 2003-54245    Patent reference literature 2: Japanese Unexamined Patent Publication No. 2002-172925    Patent reference literature 3: Japanese Unexamined Patent Publication No. 2002-41164